Nail decoration has been known to people since the earliest civilizations. Since nail polish first appeared thousands of years ago, its composition has changed significantly – today’s formulations are much more complex. In this thesis, we examined the structure of the nail and categorized nail products into basic types. We focused on their differences, application/removal methods, and availability to regular consumers. We analyzed the composition of 35 products and divided them into 5 groups based on purpose: 1 Disinfecting and dehydrating liquids for the nail plate, 2 Base coats, 3 Ultraviolet (UV) hard gels/polygels/acrylic powders, 4 Color gel polishes and 5 Top coats. The toxicological profile of the 7 most common ingredients was assessed. Group 1 most often included ethyl acetate (present in 14.3% of all 35 products), acetone (8.6%), and isopropanol (14.3%). We assessed the toxicology of the latter two, both showing similar toxicity and no risk when used as intended in cosmetics. Group 2 most often had p-hydroxyanisole (37.1%), hydroxypropyl methacrylate (31.4%), isobornyl methacrylate (25.7%), and hydroquinone (31.4%). We evaluated hydroquinone – low dermal toxicity but is irritating and phototoxic. It is limited to 0.02% in cosmetic formulations with a required professional use label, but was freely available in the products reviewed. In group 3, besides p-hydroxyanisole, the most appeared are hydroxycyclohexyl phenyl ketone (45.7%), di-HEMA trimethylhexyl dicarbamate (37.1%), and trimethylbenzoyl diphenylphosphine oxide (25.7%). We assessed the latter two. p-Hydroxyanisole has a similar toxicological profile to hydroquinone (low dermal toxicity, irritating, and phototoxic), with the same restrictions and accessibility issues. The same applies to trimethylbenzoyl diphenylphosphine oxide, only its allowed concentration is higher (5%) since it is neither irritating nor phototoxic. In group 4, the most common are hydroxycyclohexyl phenyl ketone (45.7%) and 2-hydroxyethyl methacrylate (HEMA; 42.9%). We evaluated HEMA – it has low dermal toxicity, though skin irritation and phototoxicity are not fully confirmed. It is also restricted to professional use, yet widely freely available. In group 5, a very frequent compound is hydroxypropyl methacrylate (HPMA; 31.4%). We evaluated the safety of HPMA – it has low dermal toxicity, is potentially phototoxic, and can irritate the skin. However, with correct use, it poses no major risk. In conclusion, some reviewed products contain substances that may pose risks when misused or used by untrained individuals, making them suitable for professional salons only. Products without these substances are safe for regular consumer use.
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